In a stretcher, which is loaded on an ambulance car for carrying an emergency patient, the front and rear leg sections of the stretcher are folded and loaded onto the ambulance car. Particularly, in the matter of urgency, the leg sections are required to have such folding structure that allows the stretcher to be readily loaded onto the ambulance car and unloaded therefrom. Further, since the stretcher is used for carrying a patient with an advanced disease or an emergency patient, the leg sections of the stretcher are required to have a structure such that, when the stretcher is loaded onto the ambulance car, the folding structure functions gently so as not to give any pain or uneasiness to the patient. Further, it is conceivable that the loading and unloading work of the emergency patient is carried out in a various situation. Therefore, such a slide mechanism capable of swiftly adjusting the height of the stretcher table of the stretcher to an appropriate position is also required.
Conventionally, as for a sliding system for raising and lowering the stretcher table of the stretcher, an oil spring type with lock, in which a pin is engaged with a hole to lock the stretcher table of the stretcher at a desired height, is employed. The above system has the following disadvantage. That is, the positions for adjusting and securing the height are limited to the positions formed with holes. Therefore, in order to reduce the distance for loading a patient onto a stretcher table of the stretcher as short as possible, various methods for adjusting the height of the stretcher table in a stepless manner has been proposed.
Patent document 1 discloses the following stretcher in a claim. That is, “a stretcher having castors on the front portion and the rear portion, comprising: an upper frame for loading a litter on its upper portion and a slide mechanism for vertically shifting the position of the upper frame, wherein, as a stepless stopper mechanism for stopping the slide in the slide mechanism in a stepless manner, a front-leg slide mechanism provided to a lower portion of the upper frame, and a rear-leg slide mechanism is provided to a rear-leg.”
Patent document 2 discloses a stretcher in claim 1, which employs the following structure; i.e., “an under carriage, comprising a support structure attached to a frame structure capable of adjusting its height including a pair of first and second legs capable of being folded and an operating device for adjusting the height of the support structure, wherein the operating device includes a coupling device connected to the pair of first and second legs capable of being folded and the support structure, the coupling device is capable of being retracted or elongated to adjust the height of the support structure by extending or folding the pair of first and second legs.” The device for vertically shifting the stretcher has the following structure. That is, “since the flexible coupling is energized being wound around on each spool, the spool is maintained under an appropriate spring tension. Each spool is provided with a ratchet mechanism and is arranged so that, when the ratchet mechanism is disengaged so as to allow the support structure to descend, the flexible coupling is released from the spool (pp. 3, left-upper column, 2nd line).” To release the flexible coupling from the spool, “the ratchet mechanism is provided with a cogwheel of a saw blade secured to the shaft of the spool so as to prevent the spool from rotating by a hook which engages with the saw blade as shown in FIG. 7 (pp. 4, lower-left column, 3rd line).”
Further, the patent document 3 claims the following stretcher in claim 1; “a main stretcher legs uprising mechanism comprising a gas damper with lock and a slide shaft pusher plate.” The following structure is described; i.e., “as shown in FIG. 1, a gas damper with lock is secured to a lock & slide carrier assembly and a corresponding slide shaft pusher plate is secured to an I-beam. Likewise, a gas damper with lock is secured to the main frame and a corresponding slide shaft pusher plate is secured to a lock & slide carrier assembly (pp. 5, first line).
In the stretcher, which is loaded on an ambulance car, such structure that an emergency patient laid on the litter can be stably placed on the stretcher and swiftly loaded onto ambulance car without giving the emergency patient any pain or uneasiness is required. To achieve the above object, various inventions as described above have been proposed. However, it is desired to provide a new stretcher with a higher safe, which, when the stretcher is made vertically slide to adjust its height, makes less vibration and permits the ambulance crews to reliably operate the stretcher.
Patent document 1: International Publication No. WO02/051347
Patent document 2: Published patent application H07-504838, pp. 2
Patent document 3: Japanese Utility Model Registration No. 3058160, pp. 2